“To estimate whether marijuana use in pregnancy increases risks for adverse neonatal outcomes and clarify if any increased risk is attributable to marijuana use itself or to confounding factors such as tobacco use.

CONCLUSION:

Maternal marijuana use during pregnancy is not an independent risk factor for adverse neonatal outcomes after adjusting for confounding factors.

Thus, the association between maternal marijuana use and adverse outcomes appears attributable to concomitant tobacco use and other confounding factors.”

http://www.ncbi.nlm.nih.gov/pubmed/27607879

“Using Pot While Pregnant Not Tied to Birth Risks. Smoking marijuana during pregnancy doesn’t appear to increase the risk of preterm birth or other harmful birth outcomes, a new review study suggests.” http://www.livescience.com/56036-marijuana-pregnant-preterm-birth-risk.html

“Marijuana Is Safe During pregnancy, Experts Do Not Encourage. Marijuana does not increase pregnancy risk according to new research. It does not have a negative outcome when it comes to premature birth and low birth weight. Still, experts do not encourage marijuana use during pregnancy.” http://www.scienceworldreport.com/articles/47194/20160910/marijuana-safe-during-pregnancy-experts-encourage.htm